Estimating pose in 3d space

ABSTRACT

Methods and devices for estimating position of a device within a 3D environment are described. Embodiments of the methods include sequentially receiving multiple image segments forming an image representing a field of view (FOV) comprising a portion of the environment. The image includes multiple sparse points that are identifiable based in part on a corresponding subset of image segments of the multiple image segments. The method also includes sequentially identifying one or more sparse points of the multiple sparse points when each subset of image segments corresponding to the one or more sparse points is received and estimating a position of the device in the environment based on the identified the one or more sparse points.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of priority under 35 U.S.C. §119(e)to U.S. Provisional Patent Application No. 62/357,285 filed Jun. 30,2016, entitled “ESTIMATING POSE IN 3D SPACE,” the contents of which arehereby incorporated by reference herein in their entirety.

FIELD

The present disclosure relates to virtual reality and augmented realityimaging and visualization systems and more particularly to sparse poseestimation in three-dimensional (3D) space.

BACKGROUND

Modern computing and display technologies have facilitated thedevelopment of systems for so called “virtual reality” or “augmentedreality” experiences, wherein digitally reproduced images or portionsthereof are presented to a user in a manner wherein they seem to be, ormay be perceived as, real. A virtual reality, or “VR”, scenariotypically involves presentation of digital or virtual image informationwithout transparency to other actual real-world visual input; anaugmented reality, or “AR”, scenario typically involves presentation ofdigital or virtual image information as an augmentation to visualizationof the actual world around the user. For example, referring to FIG. 1,an augmented reality scene 1000 is depicted wherein a user of an ARtechnology sees a real-world park-like setting 1100 featuring people,trees, buildings in the background, and a concrete platform 1120. Inaddition to these items, the user of the AR technology also perceivesthat he “sees” a robot statue 1110 standing upon the real-world platform1120, and a cartoon-like avatar character 1130 flying by which seems tobe a personification of a bumble bee, even though these elements do notexist in the real world. As it turns out, the human visual perceptionsystem is very complex, and producing a VR or AR technology thatfacilitates a comfortable, natural-feeling, rich presentation of virtualimage elements amongst other virtual or real-world imagery elements ischallenging. Systems and methods disclosed herein address variouschallenges related to VR and AR technology.

SUMMARY

One aspect of the present disclosure provides sparse pose estimationperformed as sparse points are captured in an image frame by an imagecapture device. Accordingly, the sparse pose estimation can be performedbefore the entire image frame has been captured. In some embodiments,the sparse pose estimation may be refined or updated as the image frameis captured.

In some embodiments, systems, devices, and methods for estimating aposition of an image capture device within an environment are disclosed.In some implementations, the method may include sequentially receiving afirst group of multiple image segments. The first group of multipleimage segments may form at least a portion of an image representing afield of view (FOV) from in front of an image capture device, which mayinclude a portion of the environment surrounding the image capturedevice and multiple sparse points. Each sparse point may correspond to asubset of image segments. The method may also include identifying afirst group of sparse points, which includes one or more sparse pointsthat are identified as the first group of multiple image segments arereceived. The method may then include determining, by a positionestimation system, the position of the image capture device within theenvironment based on the first group of sparse points. The method mayalso include sequentially receiving a second group of multiple imagesegments, which may be received after the first group of multiple imagesegments and form at least another portion of the image. The method maythen include identifying a second group of sparse points, which mayinclude one or more sparse points that are identified as the secondgroup of multiple image segments are received. The method may thenupdate, by the position estimation system, the position of the imagecapture device within the environment based on the first and secondgroup of sparse points.

In some embodiments, systems, devices, and methods for estimating aposition of an image capture device within an environment are disclosed.In some implementations, a method may include sequentially receivingmultiple image segments, which may form an image representing a field ofview (FOV) from in front of the image capture device. The FOV mayinclude a portion of the environment surrounding the image capturedevice and include multiple sparse points. Each sparse point may beidentifiable based in part on a corresponding subset of image segmentsof the multiple image segments. The method may also include sequentiallyidentifying one or more sparse points of the multiple sparse points wheneach subset of image segments corresponding to the one or more sparsepoints is received. The method may then include estimating a position ofthe image capture device in the environment based on the identified theone or more sparse points.

In some embodiments, systems, devices, and methods for estimating aposition of an image capture device within an environment are disclosed.In some implementations, an image capture device may include an imagesensor configured to capture an image. The image may be captured viasequentially capturing multiple image segments that represent a field ofview (FOV) of the image capture device. The FOV may include a portion ofthe environment surrounding the image capture device and a plurality ofsparse points. Each sparse point may be identifiable based in part on acorresponding subset of the multiple image segments. The image capturedevice may also include a memory circuit configured to store the subsetsof image segments corresponding to one or more sparse points and acomputer processor operatively coupled to the memory circuit. Thecomputer processor may be configured to sequentially identify one ormore sparse points of the multiple sparse points when each subset ofimage segments corresponding to the one or more sparse points isreceived by the image capture device. The computer processor may also beconfigured to extract the sequentially identified one or more sparsepoints for estimating a position of the image capture device in theenvironment based on the identified the one or more sparse points.

In some embodiments, systems, devices, and methods for estimating aposition of an image capture device within an environment are disclosed.In some implementations, an augmented reality system is disclosed. Theaugmented reality system may include an outward-facing imaging device,computer hardware, and a processor operatively coupled to the computerhardware and outward-facing imaging device. The processor may beconfigured to execute instructions to perform at least a portion of themethods disclosed herein.

In some embodiments, systems, devices, and methods for estimating aposition of an image capture device within an environment are disclosed.In some implementations, an autonomous entity is disclosed. Theautonomous entity may include an outward-facing imaging device, computerhardware, and a processor operatively coupled to the computer hardwareand outward-facing imaging device. The processor may be configured toexecute instructions to perform at least a portion of the methodsdisclosed herein.

In some embodiments, systems, devices, and methods for estimating aposition of an image capture device within an environment are disclosed.In some implementations, a robotic system is disclosed. The roboticsystem may include an outward-facing imaging device, computer hardware,and a processor operatively coupled to the computer hardware andoutward-facing imaging device. The processor may be configured toexecute instructions to perform at least a portion of the methodsdisclosed herein.

Various implementations of methods and apparatus within the scope of theappended claims each have several aspects, no single one of which issolely responsible for the desirable attributes described herein.Without limiting the scope of the appended claims, some prominentfeatures are described herein.

Details of one or more implementations of the subject matter describedin this specification are set forth in the accompanying drawings and thedescription below. Other features, aspects, and advantages will becomeapparent from the description, the drawings, and the claims. Neitherthis summary nor the following detailed description purports to defineor limit the scope of the inventive subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 depicts an illustration of an augmented reality scenario withcertain virtual reality objects, and certain actual reality objectsviewed by a person.

FIG. 2 schematically illustrates an example of a wearable displaysystem.

FIG. 3 schematically illustrates an example of a plurality of positionsof an imaging device as it moves in a 3D space (a room in this example).

FIGS. 4A and 4B schematically illustrate an example of a shearing effecton an image frame.

FIGS. 5A and 5B schematically illustrate an example of the shearingeffect of FIGS. 4A and 4B on multiple sparse points.

FIG. 6 is a block diagram of an example AR architecture.

FIG. 7 is an example coordinate system for pose.

FIG. 8 is a process flow diagram of an example of a method ofdetermining a pose of an imaging device in a 3D space.

FIGS. 9A and 9B schematically illustrate an example of extracting one ormore sparse points from an image frame based on receiving multiple imagesegments.

FIG. 10 is a process flow diagram of another example of a method ofdetermining a pose of an imaging device in a 3D space.

Throughout the drawings, reference numbers may be re-used to indicatecorrespondence between referenced elements. The drawings provided arenot to scale and are provided to illustrate example embodimentsdescribed herein and are not intended to limit the scope of thedisclosure.

DETAILED DESCRIPTION Overview

With the use of the AR devices, or other devices that move within athree dimensional (3D) space, the device may need to track its movementthrough the 3D space and map the 3D space. For example, the AR devicemay be moved about the 3D space, either due to movement of a user orindependent of a user (e.g., a robot or other autonomous entity), and,to facilitate display of virtual image elements among other virtualimage elements or real-world image elements, it may be beneficial to mapthe 3D space and determine one or more of the location, position, ororientation of the device within the 3D space for subsequent processing.For example, to accurately present the virtual and real-world imageelements, the device may need to know where it is located and at whatorientation within the real-world and accurately render a virtual imagein a particular location with a particular orientation within thereal-world space. In another embodiment, it may be desirable toreproduce to the trajectory of the device through the 3D space. Thus, itmay be desirable to determine, in real-time as the device moves aboutthe 3D space, a position, location, or orientation (hereinafter referredto collectively as a “pose”) of the device within the 3D space. In someimplementations, sparse pose estimation within the 3D space may bedetermined from a continuous stream of image frames from an imagingdevice included as part of, for example, the AR device. Each image frameof the continuous stream may be stored for processing, and also toestimate the pose of the device therefrom for inclusion in the sparsepose estimation. However, these techniques may cause delays inestimating pose due to transferring the entirety of each frame to amemory for subsequent processing.

The present disclosure provides example devices and methods configuredto estimate a pose of a device (e.g., an AR device or an autonomousdevice such as a robot) within a 3D space. As one example, the devicemay perform sparse pose estimation based on receiving multiple imageframes and estimating the pose of the device from each image frame asthe device moves through the 3D space. Each image frame may represent aportion of the 3D space in front of the device indicative of a positionof the device within the 3D space. In some embodiments, each image framemay include one or more of features or objects that may be representedby sparse points, keypoints, point clouds, or other types ofmathematical representations. For each image frame, an image frame maybe captured by sequentially receiving multiple image segments that, whencombined, make up the entire image frame. Therefrom, the device may beconfigured to identify the sparse points within the image frame uponreceiving the image segments comprising each sparse point. The devicemay extract a first group of sparse points, comprising one or moresparse points. The first group of sparse points may be at least oneinput to a sparse pose estimation process. Subsequently, the device mayidentify and extract a second group of sparse points and update thesparse pose estimation based on the second group. In one exampleimplementation, the first group of sparse points may be utilized toestimate the pose of the device prior to identifying subsequent sparsepoints (e.g., the second group of sparse points). Subsequent sparsepoints may become available for use in updating the sparse poseestimation as they are identified.

While embodiments of the methods, devices, and systems are describedherein with reference to an AR device, this is not intended to limit thescope of the disclosure. The methods and devices described herein arenot limited to an AR device or a head mounted device; other devices arepossible (for example, mobile robotics, a digital camera, autonomousentities, etc.). Applicable devices include, but are not limited to,such device capable of moving, independently or by user intervention,through a 3D space. For example, the methods described herein may beapplied to an object moved about a 3D space that is tracked by camerasthat are remote to the object. In some embodiments, the processing mayalso be performed remote to the object.

Example AR Device for Moving in a 3D Space

In order for a 3D display to facilitate a comfortable, natural-feeling,rich presentation of virtual image elements among other virtual orreal-world imagery elements, it is desirable to map the real-worldsurrounding the display and to reproduce the trajectory of the displaythrough the 3D space. For example, a sparse pose estimation process maybe performed to determine the map of the 3D space. If the sparse poseestimation is not performed in real-time with minimal delay, the usermay experience unstable imaging, harmful eyestrain, headaches, andgenerally unpleased VR and AR viewing experience. Accordingly, variousembodiments described herein are configured to determine or estimate oneor more of the position, location, or orientation of an AR device.

FIG. 2 illustrates an example of wearable display system 100. Thedisplay system 100 includes a display 62, and various mechanical andelectronic modules and systems to support the functioning of display 62.The display 62 may be coupled to a frame 64, which is wearable by adisplay system user, wearer, or viewer 60 and which is configured toposition the display 62 in front of the eyes of the viewer 60. Thedisplay system 100 can comprise a head mounted display (HMD) that isworn on the head of the wearer. An augmented reality display (ARD) caninclude the wearable display system 100. In some embodiments, a speaker66 is coupled to the frame 64 and positioned adjacent the ear canal ofthe user (in some embodiments, another speaker, not shown, may bepositioned adjacent the other ear canal of the user to provide forstereo/shapeable sound control). The display system 100 can include oneor more outward-facing imaging systems 110 that observe the world in theenvironment (e.g., a 3D space) around the wearer. The display 62 can beoperatively coupled by a communications link 68, such as by a wired leador wireless connectivity, to a local processing and data module 70 whichmay be mounted in a variety of configurations, such as fixedly attachedto the frame 64, fixedly attached to a helmet or hat worn by the user,embedded in headphones, or otherwise removably attached to the user 60(e.g., in a backpack-style configuration, in a belt-coupling styleconfiguration).

The display system 100 may comprise one or more outward-facing imagingsystems 110 a or 110 b (individually or collectively referred tohereinafter as “110”) disposed on the frame 64. In some embodiments, theoutward-facing imaging system 110 a can be disposed at approximately acentral portion of the frame 64 between the eyes of the user. In anotherembodiment, alternatively or in combination, the outward-facing imagingsystem 110 b can be disposed on one or more sides of the frame adjacentto one or both eyes of the user. For example, an outward-facing imagingsystem 110 b may be located on both the left and right side of the useradjacent to both eyes. While example arrangements of the outward-facingcamera 110 are provided above, other configurations are possible. Forexample, the outward facing imaging system 110 may be positioned in anyorientation or position relative to the display system 100.

In some embodiments, the outward-facing imaging system 110 captures animage of a portion of the world in front of the display system 100. Theentire region available for viewing or imaging by a viewer may bereferred to as the field of regard (FOR). In some implementations, theFOR may include substantially all of the solid angle around the displaysystem 100 because the display may be moved about the environment toimage objects surrounding the display (in front, in back, above, below,or on the sides of the wearer). The portion of the FOR in front of thedisplay system may be referred to as the field of view (FOV) and theoutward-facing imaging system 110 is sometimes referred to as an FOVcamera. Images obtained from the outward-facing imaging system 110 canbe used to identify sparse points of the environment and estimate thepose for use in a sparse pose estimation process, and so forth.

In some implementations, the outward-facing imaging system 110 may beconfigured as a digital camera comprising an optical lens system and animage sensor. For example, light from the world in front of the display62 (e.g., from the FOV) may be focused by the lens of the outward-facingimaging system 110 onto the image sensor. In some embodiments, theoutward-facing imaging system 100 may be configured to operate in theinfrared (IR) spectrum, visible light spectrum, or in any other suitablewavelength range or range of wavelengths of electromagnetic radiation.In some embodiments, the imaging sensor may be configured as either aCMOS (complementary metal-oxide semiconductor) or CCD (charged-coupleddevice) sensor. In some embodiments, the image sensor may be configuredto detect light in the IR spectrum, visible light spectrum, or in anyother suitable wavelength range or range of wavelengths ofelectromagnetic radiation. In some embodiments, the frame rate of thedigital camera may relate to a rate that image data can be transmittedfrom the digital camera to the memory or storage unit (e.g., localprocessing and data module 70). For example, if the frame rate of thedigital camera is 30 hertz, then data captured by the pixels of theimage sensor may be read into the memory (e.g., clocked off) every 30milliseconds. Thus, the frame rate of the digital camera may impart adelay into the storing and subsequent processing of image data.

In some embodiments, where the outward-facing imaging system 110 is adigital camera, the outward-facing imaging system 110 may be configuredas a global shutter camera or a rolling shutter (e.g., also referred toas a progressive scan camera). For example, where the outward-facingimaging system 110 is a global shutter camera, the image sensor may be aCCD sensor configured to capture an entire image frame representative ofthe FOV in front of the display 62 in a single operation. The entireimage frame may then be read into the local processing and data module70 for processing, for example, performing sparse pose estimation asdescribed herein. Accordingly, in some embodiments, utilizing the entireimage frame may impart a delay into the pose estimation, for example,due to the frame rate and delay in storing the image, as describedabove. For example, a global shutter digital camera having a 30 hertzframe rate may impart a 30 millisecond delay before any pose estimationcan be performed.

In other embodiments, where the outward-facing imaging system 110 isconfigured as rolling shutter camera, the image sensor may be a CMOSsensor configured to sequentially capture a plurality image segments andscan across the scene to transmit image data of the captured imagesegments. The image segments, when combined in the order captured, makeup the image frame of the FOV of the outward facing imaging system 110.In some embodiments, the scan direction may be horizontal, for example,the outward-facing imaging system 110 may capture a plurality ofvertical image segments that are horizontally adjacent in a leftward orrightward direction. In another embodiment, the scan direction may bevertical, for example, the outward-facing imaging system 110 may capturea plurality of horizontal image segments that are vertically adjacent inan upward or downward direction. Each image segment may be sequentiallyread into the local processing and data module 70 as the respectiveimage segment is captured at the image sensor. Accordingly, in someembodiments, the delay due to the frame rate of a digital camera, asdescribed above, may be reduced or minimized by sequentiallytransmitting the image segments as they are captured by the digitalcamera.

The local processing and data module 70 may comprise one or morehardware processors, as well as digital memory, such as non-volatilememory (e.g., flash memory), both of which may be utilized to assist inthe processing, buffering, caching, and storage of data. The data mayinclude data a) captured from sensors (which may be, e.g., operativelycoupled to the frame 64 or otherwise attached to the user 60), such asimage capture devices (e.g., outward-facing imaging system 110),microphones, inertial measurement units (IMUs), accelerometers,compasses, global positioning system (GPS) units, radio devices, and/orgyroscopes; and/or b) acquired and/or processed using remote processingmodule 72 and/or remote data repository 74, possibly for passage to thedisplay 62 after such processing or retrieval. The local processing anddata module 70 may be operatively coupled by communication links 76and/or 78, such as via wired or wireless communication links, to theremote processing module 72 and/or remote data repository 74 such thatthese remote modules are available as resources to the local processingand data module 71. In addition, remote processing module 72 and remotedata repository 74 may be operatively coupled to each other. In someembodiments, the local processing and data module 70 may be operablyconnected to one or more of the image capture devices, microphones,inertial measurement units, accelerometers, compasses, GPS units, radiodevices, and/or gyros. In some other embodiments, one or more of thesesensors may be attached to the frame 64, or may be standalone structuresthat communicate with the local processing and data module 70 by wiredor wireless communication pathways.

In some embodiments, the digital memory of local processing and datamodule 70 or a portion thereof may be configured to store one or moreelements of data for a temporary period of time (e.g., as anon-transitory buffer storage). For example, the digital memory may beconfigured to receive some or all of the data and store some or all ofthe data for a short-term period of time while the data is moved betweenprocesses of the local processing and data module 70. In someimplementations, a portion of the digital memory may be configured as abuffer that sequentially receives one or more image segments from theoutward-facing imaging system 110. Accordingly, the buffer may be anon-transitory data buffer configured to store a set number of imagesegments (as described below with reference to FIGS. 9A and 9B) prior tothe image segments being transmitted to the local processing and datamodule 70 (or remove data repository 74) for permanent storage orsubsequent processing.

In some embodiments, the remote processing module 72 may comprise one ormore hardware processors configured to analyze and process data and/orimage information. In some embodiments, the remote data repository 74may comprise a digital data storage facility, which may be availablethrough the internet or other networking configuration in a “cloud”resource configuration. In some embodiments, the remote data repository74 may include one or more remote servers, which provide information,e.g., information for generating augmented reality content, to the localprocessing and data module 70 and/or the remote processing module 72. Insome embodiments, all data is stored and all computations are performedin the local processing and data module 70, allowing fully autonomoususe from a remote module.

While an example AR device is described herein, it will be understoodthat the methods and devices disclosed herein are not limited to ARdevices or head mounted devices. Other configurations are possible, forexample, mobile robotics, a digital camera, autonomous entities, etc.Applicable devices include, but are not limited to, such devices capableof moving, independently or by use intervention, through a 3D space.

Example Trajectory of AR Device Through a 3D Space

FIG. 3 schematically illustrates an imaging device 310 as it movesthrough a 3D space 300. For example, FIG. 3 shows the imaging device 310at multiple positions 312 (e.g., 312 a, 312 b, 312 c, and 312 d) andorientations within environment 300 as the imaging device 310 movesalong the dotted line that schematically represents a trajectory 311. Ateach position 312, the imaging device 310 may be configured to capturean image frame of the environment 300 of a particular location andorientation, which may be used as a continuous stream of image frames,for example, for performing sparse pose estimation. The trajectory 311may be any trajectory or path of movement through the environment 300.While FIG. 3 illustrates four positions 312, the number of positions canbe different. For example, the number of positions 312 may be as few astwo positions or as many as desired to perform the sparse poseestimation with an acceptable level of certainty (e.g., 5, 6, 7, etc.).In some embodiments, the imaging device 312 may be configured to capturea series of image frames, for example, as in a video, where each imageframe of the video may be utilized to perform sparse pose estimation viacomputer vision techniques as described herein.

In some embodiments, the imaging device 310 may be configured as adisplay system 100 of FIG. 1, comprising an outward-facing imagingsystem 110, a mobile robot including an imaging system, or as anindependent imaging device. The imaging device 310 may be configured tocapture image frames at each position 312 depicting a portion of theenvironment 300 from in front of the imaging device 310 as its movesthrough the environment 300. As described above, the portion of theenvironment 300 captured by the imaging device at each position 312 andorientation may be the FOV from in front of the imaging device 310. Forexample, the FOV of the position 312 a is schematically illustrated asFOV 315 a. Each subsequent position and orientation (e.g., 312 b, 312 c,and 312 d) of imaging device 310 comprises a corresponding FOV 315(e.g., FOV 315 b, 315 c, and 315 d). Computer vision techniques may beperformed on each image frame obtained from the imaging device 310 toestimate a pose of the imaging device 310 at each position 312. The poseestimation may be an input to a sparse point estimation process employedto, for example, determine or generate a map (or portions thereof) ofthe environment 300 and track the movement of the imaging device 310through the environment 300.

The environment 300 may be any 3D space, for example, an office room (asillustrated in FIG. 3), a living room, an outdoor space, etc. Theenvironment 300 may comprise a plurality of objects 325 (e.g.,furniture, personal items, surrounding structures, textures, detectablepatterns, etc.) disposed throughout the environment 300. The objects 325may be individual objects that are uniquely identifiable as compared toother features in the environment (e.g., each wall may not be uniquelyidentifiable). Furthermore, the objects 325 may be common featurescaptured in two or more image frames. For example, FIG. 3 illustrates anobject 325 a (a lamp in this example) located in each of the FOV 315 ofthe imaging device 310 at each position 312 along a corresponding lineof sight 330 a-d (shown, for illustrative purposes, as a dotted line).Thus, for each position 312 (e.g., 312 a) the image frame representativeof each FOV 315 (e.g., 315 a) includes the object 325 a as imaged alongline of sight 330 (e.g., 330 a).

The imaging device 310 may be configured to detect and extract aplurality of sparse points 320, each sparse point 320 (or multiplesparse points) corresponding to an object 325 or portion, texture, orpattern of the object 325, from each image frame representing an FOV315. For example, the imaging device 310 may extract a sparse point 320a corresponding to object 325 a. In some embodiments, the object 325 amay be associated with one or more sparse points 320, where each sparsepoint 320 may be associated with a different portion of object 325(e.g., a corner, top, bottom, side, etc. of the lamp). Accordingly, eachsparse point 320 may be uniquely identifiable within the image frame.Computer vision techniques can be used to extract and identify eachsparse point 320 from the image frame or image segments corresponding toeach sparse point 320 (e.g., as described in connection to FIGS. 9A and9B).

In some embodiments, the sparse points 320 may be utilized to estimatethe position, location, or orientation of the imaging device 310 withinthe environment 300. For example, the imaging device 310 may beconfigured to extract a plurality of sparse points 320 as inputs into toa sparse pose estimation process. An example computer vision techniqueused for sparse pose estimation may be a simultaneous localization andmapping (SLAM or V-SLAM, referring to a configuration wherein the inputis images/visual only) process or algorithm. Such example computervision techniques can be used to output a sparse point representation ofthe world surrounding the imaging device 310, as described in moredetail below. In a conventional sparse pose estimation system using themultiple image frames of positions 312, sparse points 320 may becollected from each image frame, correspondences are computed betweensuccessive image frames (e.g., position 312 a to 312 b), and posechanges are estimated based on the correspondences discovered.Accordingly, in some embodiments, the position, orientation, or bothposition and orientation of the imaging device 310 can be determined. Insome implementations, a 3D map of the locations of the sparse points maybe required for the estimation process or may be a byproduct ofidentifying sparse points in an image frame or multiple image frames. Insome embodiments, the sparse points 320 may be associated with one ormore descriptors, which may be configured as digital representations ofthe sparse points 320. In some embodiments, the descriptors may beconfigured to facilitate the computation of correspondence between thesuccessive image frames. In some embodiments, the pose determination maybe performed by a processor on board the imaging device (e.g., localprocessing and data module 70) or remote to the imaging device (e.g.,remote processing module 72).

In some embodiments, a computer vision module can be included inoperable communication with the imaging device 310, for example, as partof the local processing and data module 70 or the remote processingmodule and data repository 72, 74. Example computer vision modules canimplement one or more computer vision techniques and can be used toanalyze the image segments obtained by the outward facing imagingcameras, e.g., to identify sparse points, determine pose, etc., forexample as described with reference to the methods 800, 1000 of FIGS. 8and 10. The computer vision module can identify objects in theenvironment surrounding the imaging device 310, such as those describedin connection to FIG. 3. The computer vision module can extract sparsepoints from an image frame and use the extracted sparse points fortracking and identifying the object through various image frames as theimaging device moves in the environment. For example, sparse points of afirst image frame may be compared to sparse points of a second imageframe to track the movement the imaging device. In some embodiments, oneor more sparse points of the second image frame may include one or moreof the sparse points of the first image frame, for example, as areference point for tracking between the first and second image frames.Third, fourth, fifth, etc. image frames may be similarly used andcompared to previous and subsequent image frames. The computer visionmodule can process the sparse points to estimate the position ororientation of the imaging device within the environment based on theidentified sparse points. Non-limiting examples of computer visiontechniques include: Scale-invariant feature transform (SIFT), speeded uprobust features (SURF), oriented FAST and rotated BRIEF (ORB), binaryrobust invariant scalable keypoints (BRISK), fast retina keypoint(FREAK), Viola-Jones algorithm, Eigenfaces approach, Lucas-Kanadealgorithm, Horn-Schunk algorithm, Mean-shift algorithm, visualsimultaneous location and mapping (v-SLAM) techniques, a sequentialBayesian estimator (e.g., Kalman filter, extended Kalman filter, etc.),bundle adjustment, Adaptive thresholding (and other thresholdingtechniques), Iterative Closest Point (ICP), Semi Global Matching (SGM),Semi Global Block Matching (SGBM), Feature Point Histograms, variousmachine learning algorithms (such as e.g., support vector machine,k-nearest neighbors algorithm, Naive Bayes, neural network (includingconvolutional or deep neural networks), or other supervised/unsupervisedmodels, etc.), and so forth.

As described above, current pose estimation processes may include adelay in estimating the pose of an imaging device. For example, theframe rate of the imaging device may cause a delay, in part, due totransferring the entire image frame from the imaging device to thememory. Without subscribing to any particular scientific theory, thesparse pose estimation may be delayed because sparse points are notextracted from the image frame until the entire image frame is read tothe memory from the imaging device. Accordingly, the transfer of theentire image frame based in part on the frame rate capabilities of theimaging device may be one component of the delay experienced in sparsepose estimation. One non-limiting advantage of some of the systems anddevices described herein is that extraction or identification of sparsepoints for estimating pose may be performed on the fly as portions ofthe image frame are read into the image sensor or memory, thus pose maybe estimated at a point in time earlier than otherwise possible whenusing the entire image frame. Further, since only a portion of a framemay be analyzed for keypoints, processing speed and efficiency may beincreased.

While the foregoing description describes sparse points 320 in thecontext of physical objects in the environment 300, this is not intendedto be limiting and other implementations are possible. In someembodiments, the objects 325 may refer to any feature of the environment(e.g., real-world objects, virtual objects, non-visible objects orfeatures, etc.). For example, a projecting device may be configured toproject a plurality of indicators, textures, identifiers, etc.throughout the environment that may be visible or non-visible (e.g.,projected in the IR spectrum, near-IR spectrum, ultraviolet spectrum, orin any other suitable wavelength range or range of wavelengths ofelectromagnetic radiation). The indicators, textures, identifiers, etc.,may be a distinctive feature or shape that is detectable by the imagingdevice 310. The imaging device 310 may be configured to detect theseindicators and extract sparse points 320 from the plurality ofindicators. For example, an indicator may be projected on the wall ofthe environment in the IR spectrum of electromagnetic radiation and theimaging device 310 may be configured to operate in the IR spectrum toidentify indicator and extract sparse points therefrom. In anotherembodiment, in the alternative or in combination, the imaging device 310may be included in an AR device that is configured to display a virtualimage element (e.g., on display 62). The imaging device or the AR devicemay be configured to identify the virtual image element and extractsparse points 320 therefrom. The AR device may be configured use thesesparse points 320 to determine pose of the AR device relative to thevirtual image elements.

Example of Shear Effect Imparted into an Example Image Frame and SparsePoints

As described above, outward-facing imaging system 110 may be implementedas a rolling shutter camera. One non-limiting advantage of a rollingshutter camera is the ability to transmit portions of the captured scene(e.g., image segments) while capturing other portions (e.g., not allportions of the image frame are captured at exactly the same time).However, this may result in distortions of objects that are movingrelative to the camera while the image frame is captured because theimaging device may not be in the same position relative to the objectfor the entire time of capturing the image.

For example, FIGS. 4A and 4B are schematic illustrations of a rollingshutter effect (e.g., sometimes referred to herein as “shearing,”“shifting,” or “distortion”) applied to an image of a scene. FIG. 4Aschematically illustrates a scene 400 a comprising an object 425 a(e.g., a square in this example). The scene may be the FOV of an imagecapture device (e.g., outward-facing imaging system 110 of FIG. 2). Inthe embodiment illustrated in FIG. 4A, the scene may be moving relativeto the image capture device in a direction 430. FIG. 4B illustrates theresulting image 400 b of the captured scene 400 a that may be stored ina memory or storage unit (e.g., local processing and data module 70). Asillustrated in FIG. 4B, due to the relative movement of the object 425a, the resulting image 400 b is a distorted object 425 b (e.g., shown asa sheared square or a rhombus), where the dotted lines of the distortedobject are not captured in the resulting image 400 b. Withoutsubscribing to any particular scientific theory, this may be due to aprogressive downward scan direction of the imaging device, thus the topof the object is captured first and is less distorted than the bottom ofthe object.

FIGS. 5A and 5B are schematic illustrations of the rolling shuttereffect imparted onto a plurality of sparse points included in a FOVcaptured by an imaging device (e.g., FOV 315 a, 315 b, 315 c, or 315 dof FIG. 3). For example, as an AR device moves about the 3D space, thevarious sparse points move relative to the AR device and are distortedas schematically illustrated in FIG. 5B in a manner similar to thatdescribed above in connection with FIG. 4B. FIG. 5A illustrates a scene(e.g., which may be similar to scene 300 of FIG. 3) comprising aplurality of sparse points 320 (e.g., 320 a, 320 b, and 320 c). FIG. 4Bschematically illustrates the resulting captured image frame comprisesdistorted sparse points 525 (e.g., 525 a, 525 b, and 525 c). Forexample, each distorted sparse point 525 is associated with anillustrative corresponding arrow 522. For illustrative purposes only,the size of the arrows 522 is proportional to the amount of distortionimparted to the sparse points 525. Accordingly, similar to thatdescribed above in connection with FIG. 4B, the arrow 522 a is smallerthan arrow 522 e, which may be indicative that the sparse point 525 a,associated with the arrow 522 a is distorted less severely as comparedto sparse point 525 e.

Example AR Architecture

FIG. 6 is a block diagram of an example of an AR architecture 600. TheAR architecture 600 is configured to receive input (e.g., a visual inputfrom outward-facing imaging system 110, input from room cameras, etc.)from one or more imaging systems. The imaging devices not only provideimages from FOV cameras, they may also be equipped with various sensors(e.g., accelerometers, gyroscopes, temperature sensors, movementsensors, depth sensors, GPS sensors, etc.) to determine the location andvarious other attributes of the environment of the user. Thisinformation may further be supplemented with information from stationarycameras in the room that may provide images and/or various cues from adifferent point of view.

The AR architecture 600 may comprise multiple cameras 610. For example,the AR architecture 600 may include outward-facing imaging system 110 ofFIG. 1 configured to input a plurality of images captured of the FOVfrom in front the wearable display system 100. In some embodiments thecameras 610 may include a relative wide field of view or passive pair ofcameras arranged to the sides of the user's face and a different pair ofcameras oriented in front of the user to handle a stereo imagingprocess. However, other imaging systems, cameras, and arrangements arepossible.

The AR architecture 600 may also comprise a map database 630 includingmap data for the world. In one embodiment, the map database 630 maypartly reside on a user-wearable system (e.g., the local processing anddata module 70), or may partly reside at networked storage locationsaccessibly by wired or wireless network (e.g., remote data repository74). In some embodiments, the map database 630 may comprise real-worldmap data or virtual map data (e.g., including virtual image elementsdefining a virtual map or overlaid on a real-world environment). In someembodiments, computer vision techniques can be used to produce map data.In some embodiments, the map database 630 may be a preexisting map ofthe environment. In other embodiments, the map database 630 may bepopulated based on identified sparse points read into the memory andstored for comparison and processing relative to subsequently identifiedsparse points. In another embodiment, alone or in combination, the mapdatabase 630 may be a preexisting map that is dynamically updated basedon identified sparse points from one or more image frames (or portionsof the frames for a rolling shutter camera system). For example, one ormore sparse points may be used to identify objects (e.g., objects 325 ofFIG. 3) in the environment and used to populate the map with identifyingfeatures of the environment.

The AR architecture 600 may also comprise a buffer 620 configured toreceive inputs from cameras 610. The buffer 620 may be a non-transitorydata buffer, for example, that is separate from or a portion of anon-transitory data storage (e.g., local processing and data module 70of FIG. 2) and configured to store image data on a temporary basis. Thebuffer 620 may then store some or all received inputs temporarily. Insome embodiments, the buffer 620 may be configured to store one or moreportions or segments of received data before, for example, furtherprocessing is performed and the data is moved to another component ofthe AR architecture 600 (e.g., as described below in connection withFIGS. 9A and 9B). In some embodiments, image data collected by thecamera 610 may be read into the buffer 620 as a user experiences awearable display system 100 operating in the environment. Such imagedata may comprise images, or segments of images, captured by cameras610. Image data representative of the images or segments of images maythen be transmitted to and stored in the buffer 620 before beingprocessed by the local processing and data module and sent to thedisplay 62 for visualization and representation to the user of thewearable display system 100. The image data may also, alternatively orin combination, be stored in the map database 630. Or, the data may beremoved from the memory (e.g., local processing and data module 70 orremote data repository 74) after stored in the buffer 620. In oneembodiment, the buffer 620 may partly reside on a user-wearable system(e.g., the local processing and data module 70), or may partly reside atnetworked storage locations accessibly by wired or wireless network(e.g., remote data repository 74).

The AR architecture 600 may also include one or more object recognizers650. Object recognizers may be configured to crawl through the receiveddata and identify and/or tag objects, and attach information to theobjects with the help of a map database 630, for example, via computervision techniques. For example, the object recognizers may scan or crawlthrough the image data or image segments stored in the buffer 620 andidentify objects captured in the image data (e.g., objects 325 of FIG.3). The objects identified in the buffer may be tagged or descriptioninformation attached thereto with reference to the map database. The mapdatabase 630 may comprise various objects identified over time andbetween the captured image data and their corresponding objects (e.g., acomparison of objects identified in a first image frame with an objectidentified in a subsequent image frame) to generate the map database 630or used to generate a map of the environment. In some embodiments, themap database 630 may be populated with a preexisting map of theenvironment. In some embodiments, the map database 630 is stored onboard the AR device (e.g., local processing and data module 70). Inother embodiments, the AR device and the map database can be connectedto each other through a network (e.g., LAN, WAN, etc.) to access a cloudstorage (e.g., remote data repository 74).

In some embodiments, the AR architecture 600 comprises a pose estimationsystem 640 configured to execute instructions to carry out a poseestimation process based on, in part, data stored in the buffer 620 andthe map database 630 to determine location and orientation of thewearable computing hardware or device. For example, position, location,or orientation data may be computed from data collected by camera 610 asit is read into buffer 620 as the user is experiencing the wearabledevice and operating in the world. For example, based on the informationand collection of objects identified from the data and stored in thebuffer 620, the object recognizer 610 may recognize objects 325 andextract these objects as sparse points 320 to the processor (e.g., localprocessing and data module 70). In some embodiments, the sparse points320 may be extracted as one or more image segments of a given imageframe are read into the buffer 620 and used to estimate the pose of theAR device in the associated image frame. The estimation of the pose maybe updated as additional image segments of the image frame are read intothe buffer 620 and used to identify additional sparse points.Optionally, in some embodiments, the pose estimation system 640 mayaccess the map database 630 and retrieve sparse points 320 identified inprior captured image segments or image frames and compare thecorresponding sparse points 320 between prior and subsequent imageframes as the AR device moves through the 3D space, thereby tracking themovement, position, or orientation of the AR device in the 3D space. Forexample, referring to FIG. 3, the object recognizer 650 may recognize,in each of a plurality of image frames, a sparse point 320 a as a lamp325 a. The AR device may attach some descriptor information to associatethe sparse point 320 a in one image frame to corresponding sparse points320 a of other image frames, and store this information in the mapdatabase 650. The object recognizer 650 may be configured to recognizeobjects for any number of sparse points 320, for example, 1, 2, 3, 4,etc., sparse points.

Once the objects are recognized, the information may be used by the poseestimation system 640 to determine a pose of the AR device. In oneembodiment, the object recognizers 650 may identify sparse pointscorresponding to image segments as the image segments are received, andsubsequently may identify additional sparse points when subsequent imagesegments of the same image frame are received. The pose estimationsystem 640 may execute instructions to estimate pose based on the firstidentified sparse points and update the estimation by integrating thesubsequently identified sparse points into the estimation process. Inanother embodiment, alone or in combination, the object recognizers 650may recognize two sparse points 320 a, 320 b of two objects (e.g.,object 325 a and another object shown in FIG. 3) in a first frame, andthen identify the same two sparse points in a second frame andsubsequent frames (e.g., up to any number of subsequent frames may beconsidered). Based on a comparison between the sparse points of two ormore frames, a pose (e.g., orientation and location) within the 3D spacemay be also be estimated or tracked through the 3D space.

In some embodiments, the precision of a pose estimation, or reduction ofnoise in the pose estimation results, may be based on the number ofsparse points recognized by the object recognizers 640. For example, in3D space the position, location, or orientation of an imaging device maybe based on translational and rotational coordinates within theenvironment. Such coordinates may include, for example, X, Y, and Ztranslational coordinates or yaw, roll, pitch rotational coordinates asdescribed below in connection with FIG. 7. In some embodiments, onesparse point extracted from an image frame may not be able to convey afull pose of the imaging device. However, a single sparse point may beat least one constraint on pose estimation, for example, by providinginformation related to one or more coordinates. As the number of sparsepoints increases, the precision of the pose estimation may be improvedor the noise or errors in the pose estimation may be reduced. Forexample, two sparse points may be indicative of an X, Y position of theimaging device in a 3D space based on the object represented by thesparse point. However, the imaging device may not be able to determineits Z position relative to the object (e.g., in front of or behind theobject) or its roll coordinate. Accordingly, in some embodiments, threesparse points may be used to determine a pose, however, any number ofsparse points may be used (e.g., 1, 2, 4, 5, 6, 7, 10 or more, etc.).

In some embodiments, the pose determination may be performed by aprocessor on board the AR device (e.g., local processing and data module70). The extracted sparse points may be inputs into a pose estimationsystem 640 configured to execute computer vision techniques. In someembodiments, the pose estimation system may comprise a SLAM or V-SLAM(e.g., referring to a configuration wherein the input is images/visualonly), executed by the pose estimation system 640, which may then outputa sparse point representation 670 of the world surrounding the ARdevice. In some embodiments, the pose estimation system 640 may beconfigured to execute a continuously updated recursive Bayesianestimator (e.g., a Kalman Filter). However, the Bayesian estimator isintended as an illustrative example of at least one method forperforming pose estimation by the pose estimation system 640, and othermethods and processes are envisioned within the scope of the presentdisclosure. The system can be configured to not only find out whereinthe world the various components are, but what the world is made of. Thepose estimation may be a building block that achieves many goals,including populating the map database 630 and using the data from themap database 630. In other embodiments, the AR device can be connectedto a processor configured to perform the pose estimation through anetwork (e.g., LAN, WAN, etc.) to access a cloud storage (e.g., remotedata repository 74).

In some embodiments, one or more remote AR devices may be configured todetermine a pose of each AR device based on a pose determination of asingle AR device comprising AR architecture 600. For example, one ormore AR devices may be in wired or wireless communication with a firstAR device including AR architecture 600. The first AR device may performa pose determination based on sparse points extracted from theenvironment as described herein. The first AR device may also beconfigured to transmit an identifying signal (e.g., an IR signal orother suitable medium) that may be received by one or more remote ARdevices (e.g., a second AR device). In some embodiments, a second ARdevice may be attempting to display similar content as the first ARdevice and receive the identifying signal from the first AR device. Fromthe identifying signal, the second AR device may be able to determine(e.g., interpret or process the identifying signal) its pose relative tothe first AR device without extracting sparse points and performing poseestimation on the second AR device. One non-limiting advantage of thisarrangement is that discrepancies in virtual content displayed on thefirst and second AR devices may be avoided by linking the two ARdevices. Another non-limiting advantage of this arrangement is that thesecond AR system may be able to update its estimated position based onthe identifying signal received from the first AR device.

Example of Imaging Device Pose and Coordinate System

FIG. 7 is an example of a coordinate system for imaging device pose. Thedevice 700 may have multiple degrees of freedom. As the device 700 movestoward different directions, the position, location, or orientation ofthe device 700 will change relative to a starting position 720. Thecoordinate system in FIG. 7 shows three translational directions ofmovement (e.g., X, Y, and Z directions) that can be used for measuringthe device movement relative to the starting position 720 of the deviceto determine a location within the 3D space. The coordinate system inFIG. 7 also shows three angular degrees of freedom (e.g., yaw, pitch,and roll) that can be used for measuring the device orientation relativeto the starting direction 720 of the device. As illustrated in FIG. 7,the device 700 may also be moved horizontally (e.g., X direction or Zdirection) or vertically (e.g., Y direction). The device 700 can alsotilt forward and backward (e.g., pitching), turning left and right(e.g., yawing), and tilting side to side (e.g., rolling). In otherimplementations, other techniques or angular representations formeasuring head pose can be used, for example, any other type of Eulerangle system.

FIG. 7 illustrates a device 700 which may be implemented, for example,as a wearable display system 100, AR device, imaging device, or anyother device described herein. As described throughout the presentdisclosure, the device 700 may be used to determine the pose. Forexample, where the device 700 is an AR device comprising AR architecture600 of FIG. 6, the pose estimation system 640 may use image segmentinputs to extract sparse points for use in a pose estimation process, asdescribed above, to track the devices movement in the X, Y, or Zdirections or track the angular movement in yaw, pitch, or roll.

Example Routine for Estimating Pose in 3D Space

FIG. 8 is a process flow diagram of an illustrative routine fordetermining a pose of an imaging device (e.g., outward-facing imagingsystem 110 of FIG. 2) in a 3D space (e.g., FIG. 3), in which the imagingdevice moves. The routine 800 describes how a plurality of sparse pointsmay be extracted from an image frame representing a FOV (e.g., FOV 315a, 315 b, 315 c, or 315 d) to determine a one of position, location, ororientation of the imaging device in the 3D space.

At block 810, an imaging device may capture an input image regarding theenvironment surrounding the AR device. For example, the imaging devicemay sequentially capture a plurality of image segments of the inputimage based on light received from the surrounding environment. This maybe achieved through various input devices (e.g., digital cameras on theAR device or remote from the AR device). The input may be an imagerepresenting a FOV (e.g., FOV 315 a, 315 b, 315 c, or 315 d) and includea plurality of sparse points (e.g., sparse points 320). The FOV camera,sensors, GPS, etc., may convey information including image data ofsequentially captured image segments to the system (block 810) as theimage segments are captured by the imaging device.

At block 820, the AR device may receive the input image. In someembodiments, the AR device may sequentially receive a plurality of imagesegments forming a portion of image captured at block 810. For example,as described above, the outward-facing imaging system 110 may be arolling shutter camera configured to sequentially scan a scene therebysequentially capturing plurality of image segments and sequentiallyreads off the image data to a storage unit as the data is captured. Theinformation may be stored on the user-wearable system (e.g., the localprocessing and data module 70) or may partly reside at networked storagelocations accessibly by wired or wireless networks (e.g., remote datarepository 74). In some embodiments, the information may be temporarilystored in a buffer included in the storage unit.

At block 830, the AR device may identify one or more sparse points basedon the received image segments. For example, the object recognizer maycrawl through the image data corresponding to the received imagesegments and identify one or more objects (e.g., objects 325). In someembodiments, identifying one or more sparse points may be based onreceiving image segments corresponding to the one or more sparse points,as described below with reference to FIGS. 9A and 9B. The objectrecognizers may then extract the sparse points, which may be used asinputs for determining pose data (e.g., imaging device pose within the3D space). This information may then be conveyed to the pose estimationprocess (block 840), and the AR device may accordingly utilize the poseestimation system to map the AR device through the 3D space (block 850).

In various embodiments, the routine 800 may be performed by a hardwareprocessor (e.g., the local processing and data module 70 of FIG. 2)configured to execute instructions stored in a memory or storage unit.In other embodiments, a remote computing device (in networkcommunication with the display apparatus) with computer-executableinstructions can cause the display apparatus to perform aspects of theroutine 800.

As described above, current pose estimation processes may include adelay in estimating pose of an AR device due to transferring the data(e.g., the extracted sparse points) from the image capture device to thepose estimation system. For example, current implementations may requirethe entire image frame to be transferred from the image capture deviceto the pose estimator (e.g., SLAM, VSLAM, or similar). Once the entireimage frame is transferred, the object recognizer is permitted toidentify sparse points and extract them to the pose estimator.Transferring an entire image frame may be one contributing factor to thedelay of estimating a poser.

Example Extracting Sparse Points from Image Frames

FIGS. 9A and 9B schematically illustrate an example of extracting one ormore sparse points from an image frame based on receiving multiple imagesegments. In some implementations, FIGS. 9A and 9B may alsoschematically illustrate an example method of minimizing delay inestimating a pose of an imaging device (e.g., outward-facing imagingdevice 110 of FIG. 2) through a 3D space. In some embodiments, FIGS. 9Aand 9B also schematically depict an example of identifying one or moresparse points of an image frame 900. In some implementations, FIGS. 9Aand 9B illustrate an image frame as it is read into a storage unit froman imaging device by a rolling shutter camera, as described above. Theimage frame 900 may be captured by an outward-facing imaging system 110configured as a progressive scan imaging device. The image frame maycomprise a plurality of image segments (sometimes referred to as scanlines) 905 a to 905 n that are read into the storage unit (e.g., localprocessing and data module 70) from imaging device as the image segmentsare captured by the imaging device. The image segments may behorizontally arranged (as shown in FIG. 9A) or vertically arranged (notshown). While 15 image segments are illustrated, the number of imagesegments need not be so limited, and may be any number of image segments905 a to 905 n as desired for a given application or based on thecapabilities of the imaging system. In some implementations, an imagesegment may be a line (e.g., a row or column) in a raster scanningpattern, for example, the image segment may be a row or column of pixelsin a raster scanning pattern of an image captured by the outward-facingimaging device 110. The raster scanning pattern may be performed orexecuted by a rolling shutter camera, as described throughout thepresent disclosure.

Referring again to FIG. 9A, the image frame 900 may comprise a pluralityof image segments 905 that are sequentially captured and read into thestorage unit. The image segments 905 may be combined to represent afield of view (FOV) captured by the imaging device. The image frame 900may also comprise a plurality of sparse points 320, for example, asdescribed above with reference to FIG. 3. In some implementations, asillustrated in FIG. 9A, each sparse point 320 may be generated by one ormore image segments 905. For example, the sparse point 320 a may begenerated by subset 910 of image segments 905 and thus associatedthereto. Thus, each sparse point may be identified upon receiving thesubset of image segments 905 corresponding to each given sparse pointwhen the image segments are received at the storage unit. For example,sparse point 320 a may be identified by an object recognizer (e.g.,object recognizer 650) as soon as image segments 906 a through 906 n arereceived at the storage unit of the AR device. The image segments 906 athrough 906 n may correspond to subset 910 of image segments 905representing the sparse point 320 a. Thus, the AR device may be able todetermine individual sparse points as soon as the corresponding imagesegments have been received from the image capture device (e.g., aprogressive scan camera). The subset 910 of image segments 905 maycomprise image segments 906 a through 906 n. In some implementations,the number of image segments 906 may be based on the number of imagesegments sequentially received in a vertical direction needed to resolveor capture the entire sparse point along the vertical direction. WhileFIG. 9B illustrates 7 image segments associated with sparse point 320 a,this need not be the case and any number of image segments may beassociated with sparse point 320 a as needed to identify the object 325a corresponding to the sparse point 320 a (e.g., 2, 3, 4, 5, 6, 8, 9,10, 11, etc.).

In an example implementation, the sparse points 320 may be identified byimplementing a circular or rolling buffer. For example, the buffer maybe similar to the buffer 620 of FIG. 6. The buffer may be constructed asa portion of a memory or storage unit stored on board the AR device(e.g., local processing and data module 70) or may be remote to the ARdevice (e.g., remote data repository 74). The buffer may be configuredto receive image information from the image capture device (e.g.,outward-facing imaging system 110 of FIG. 2). For example, the buffermay sequentially receive image data representative of the image segmentsfrom the image sensor as the image sensor captures each sequential imagesegment. The buffer may also be configured to store a portion of theimage data for subsequent processing and identification of imagecontent. In some embodiments, the buffer may be configured to store oneor more image segments, wherein the number of image segments may be lessthan the total image frame 900. In some embodiments, the number of imagesegments stored in the buffer may be a predetermined number, forexample, the number in subset 910. In some embodiments, alternatively orin combination, the buffer may be configured to store a subset 910 ofimage segments corresponding to a sparse point. For example withreference to FIG. 9B, the sparse point 320 a may require a 7×7 pixelwindow (e.g., 7 rows of pixels presenting the image segments 906, whereeach image segment comprises 7 pixels). In this embodiment, the buffermay be configured to be large enough to store the subset 910 of imagesegments 906, for example, the 7 image segments illustrated.

As described above, the buffer may be configured to temporarily storeimage data. Accordingly, as new image segments are received from theimaging capture device, the older image segments are removed from thebuffer. For example, a first image segment 906 a may be received andsubsequent image segment may be received at the buffer corresponding tosparse point 320 a. Once, all image segments 906 a through 906 n arereceived, the sparse point 320 a may be identified. Subsequently, a newimage segment is received (e.g., 906 n+1) and image segment 906 a isthereby removed from the buffer. In some embodiments, the segment 906 ais moved from the buffer to storage in the digital memory (e.g., localprocessing and data module 70) for further processing.

Example Routine for Estimating Pose in 3D Space

FIG. 10 is a process flow diagram of an illustrative routine fordetermining a pose of an imaging device (e.g., outward-facing imagingsystem 110 of FIG. 2) in a 3D space (e.g., FIG. 3), in which the imagingdevice moves. The routine 1000 describes an example of how a first groupof sparse points may be extracted from an image frame as image segmentscorresponding to the sparse points of the first group of sparse pointsare received. In various embodiments, the corresponding image segmentsmay be captured prior to capturing the entire image frame representingan FOV of the imaging device. The routine 1000 also describes howsubsequent sparse points or a second group of sparse points may beextracted and integrated to update the pose determination. The routine1000 may be performed by a hardware processor (e.g., local processingand data module 70 of FIG. 2) operably coupled to an outward-facingimaging system (e.g., outward-facing imaging system 110) and a digitalmemory, or buffer, as described above. The outward-facing imaging system110 can comprise a rolling-shutter camera.

At block 1010, the imaging device may capture an input image regardingthe environment surrounding the AR device. For example, the imagingdevice may sequentially capture a plurality of image segments of theinput image based on light received from the surrounding environment.This may be achieved through various input devices (e.g., digitalcameras on the AR device or remote from the AR device). The input may bean image frame representing a FOV (e.g., FOV 315 a, 315 b, 315 c, or 315d) and include a plurality of sparse points (e.g., sparse points 320).The FOV camera, sensors, GPS, etc., may convey information includingimage data of sequentially captured image segments to the system (block1010) as the image segments are captured by the imaging device.

At block 1020, the AR device may receive the input image. In someembodiments, the AR device may sequentially receive a first plurality ofimage segments forming a portion of image captured at block 1010. Forexample, the imaging device may be configured to sequentially scan ascene thereby sequentially capturing a first plurality of image segmentsas described above with reference to FIGS. 9A and 9B. The image sensormay also sequentially read off the image data to a storage unit as thedata is captured. The information may be stored on the user-wearablesystem (e.g., the local processing and data module 70) or may partlyreside at networked storage locations accessible by wired or wirelessnetwork (e.g., remote data repository 74). In some embodiments, theinformation may be temporarily stored in a buffer included in thestorage unit.

At block 1030, the AR device may identify a first group of sparse pointsbased on receiving the first plurality of image segments (sometimesreferred to as a “pre-list”) corresponding to each sparse point. Forexample, with reference to FIGS. 9A and 9B, the AR device may identifyone or more sparse points 320 based on receiving a subset 910 of imagesegments 905 (e.g., a first plurality of image segments) correspondingto the one or more sparse points 320 as described above with referenceto FIGS. 9A and 9B. The sparse points 320 may be identified as soon asthe subset 910 of image segments 905 corresponding to the sparse points320 are received (e.g., image segments 906) at the storage unit (e.g.,local processing and data module 70).

In some implementations, the first group of sparse points comprises anarbitrary number of sparse points (N₁). The number (N₁) may be anynumber of sparse points selected to estimate the pose of the AR devicewith the environment. In some embodiments, the number (N₁) may not beless than three sparse points. In other embodiments, the number (N₁) isbetween 10 and 20 sparse points. One non-limiting advantage of a greaternumber (N₁) is that outlier data points may be rejected, which mayprovide the pose determination with some robustness to noise due toinlier data points. For example, an imaging device may be jilted orshook due to an event imparted onto the physical imaging device, or thescene being recorded could be temporarily changed (e.g., a person movingin the foreground). The event may only impact a small group of sparsepoints in one or more image frames. Using a greater number (N₁) ofsparse points or updating the pose estimation in accordance with thepresent specification, noise in the pose estimation due to theseoutliers or single instance events may be at least partially reduced.

In one implementation, the first group of sparse points may be extractedfrom the image frame (e.g., by object recognizers 650) and conveyed tothe pose estimation system (e.g., pose estimation system 640 of FIG. 6)configured to execute a pose determination (e.g., a SLAM, VSLAM, orsimilar as described above) (block 1040). In various embodiments, thefirst group of sparse points is conveyed to the pose estimation systemupon identifying the number (N₁) of sparse points based on receiving thecorresponding first plurality of image segments. Accordingly, the firstgroup of sparse points maybe conveyed when only a portion of the imageframe has been received because the imaging devices have not receivedthe entire image frame; subsequent image segments (e.g., a secondplurality of image segments obtained after the first plurality of imagesegments) remain to be received. In one embodiment, the first group ofsparse points may be extracted (e.g., from the storage unit of the ARdevice or a portion thereof, for example, the buffer) as soon as each isidentified based on scanning the corresponding subset of image segments.In another embodiment, the first group of sparse points may be extracted(e.g., from the storage unit of the AR device or the buffer) once thenumber (N₁) of sparse points is identified, and the sparse points aretransmitted in a single process.

At block 1045, the AR device may receive a second plurality of imagesegments (sometimes referred to as a “follow-list”). In someembodiments, the AR device may sequentially obtain the second pluralityof image segments after receiving the first plurality of image segmentsat block 1020. For example, the imaging device may be configured tosequentially scan a scene thereby sequentially capturing the firstplurality of image segments (e.g., block 1020) and subsequently, eitherafter or during block 1030, sequentially scanning the scene to obtainthe second plurality of image segments, as described above withreference to FIGS. 9A and 9B. In another embodiment, the secondplurality of image segments, or a portion thereof, may be obtained froma second image captured by the imaging device, the second image capturedafter the first image. The information may be stored on the AR device(e.g., the local processing and data module 70) or may partly reside atnetworked storage locations accessible by wired or wireless network(e.g., remote data repository 74). In some embodiments, the informationmay be temporarily stored in a buffer included in the storage unit.

Referring again to FIG. 10, at block 1050 the AR device may identify asecond group of sparse points based on the second plurality of imagesegments. For example, in one embodiment, the entire image frame has notbeen received prior to determining the pose at block 1040 and the secondplurality of image segments may be received from the imaging device atblock 1045. Thus, the AR device may identify one or more new sparsepoints based on receiving the second plurality of image segmentscorresponding to the one or more new sparse points (e.g., the secondgroup of sparse points) as described above with reference to FIGS. 9Aand 9B. In another embodiment, a second image may be captured by theimaging device after the first image is captured at block 1010, and thesecond plurality of image segments may be obtained from the secondimage. Thus, the AR device may identify one or more new sparse pointsbased on receiving the second plurality of image segments from thesecond image, which may correspond to the second group of sparse points.In some embodiments, the second group of sparse points may comprise anynumber of new sparse points (e.g., 1, 2, 3, etc.). In oneimplementation, the second group of sparse points may be extracted andintegrated into the pose determination, for example, by conveying thesecond group of sparse points to the pose estimation system. Below areexample methods of integrating the second group of sparse points withthe first group of sparse points into the mapping routine of FIG. 10.For example, example integration methods described herein may bereferred to as reintegration, sliding scale integration, or blockintegration. However, these example integration methods are not intendedto be exhaustive. Other methods are possible that may minimize errorsand decrease delays in the pose determination.

At block 1060, the pose estimation system may be configured to updatethe pose determination based on the pose determination at block 1040 andthe reception of the second group of sparse points at block 1050.

One non-limiting advantage of the routine 1000 described above may be areduction in the delay that results from extracting sparse points froman image frame prior to the pose estimation process. For example, bycomputing and identifying individual sparse points when the imagesegments corresponding to those sparse points are received at the buffer620, the individual or a selected group of sparse points may beextracted to, and processed by, the pose estimation system withoutwaiting for the entire image frame to be captured. Thus, the poseestimation may be performed well before the entire image is transferredto the memory and before all the sparse points can be extracted from theentire image. However, once the first group and all subsequent groups ofa particular image frame have been extracted, the entire image framewould then be available for pose estimation.

In various implementations, the second group of sparse points maycomprise a set number of sparse points identified after determining thepose at block 1040. In some embodiments, the set number may be onesparse point. For example, each time a subsequent sparse point isidentified the sparse point can be conveyed to the pose estimationsystem and a new pose estimation process performed at block 1060 toupdate one or more of the position, location, or orientation of the ARdevice. This method may sometimes be referred to as a reintegrationmethod. Accordingly, each subsequently identified sparse point mayrepresent a subsequent group of sparse points (e.g., a second, third,fourth, etc. group of sparse points). In another embodiment, the setnumber may be any number of subsequently identified sparse points (e.g.,2, 3, 4, etc.). For example, where the set number is 3, each time 3 newsparse points are identified (e.g., a subsequent group of sparsepoints), the group is conveyed to the pose estimation system at block1050 and a new pose estimation process is performed at block 1060. Thepose estimation process may thus utilize all the sparse points includedin the entire image frame.

In other implementations, integration methods may be configured toaccount for the rolling shutter effect as described above with referenceto FIGS. 4A-5B. For example, the pose estimation process may beperformed for a fixed number (N₂) of sparse points. This method maysometimes be referred to as a sliding integration method. In thisembodiment, the second group of sparse points may comprise a selectednumber (k₂) of sparse points identified after determining the pose atblock 1040. Each time a number (k₂) of sparse points may be identified,the pose determination may be updated. However, only the most recent N₂sparse points may be used to update the pose at block 1060. In someembodiments, this method utilizes the most recent N₂ sparse points,regardless of which group they correspond. For example, if N₁ is set to10, N₂ is set to 15, and k₂ is set to 5, then the first group of sparsepoints comprises the first 10 sparse points identified at block 1030.Thus, the pose is determined at block 1040 based on the first 10 sparsepoints. Subsequently, a new sparse point is identified, but the pose isnot updated. Once 5 new sparse points are identified, comprising thesecond group of sparse points, the pose may be updated based on thefirst (N₁) and second (k₂) group of sparse points. If a third group ofsparse points are identified (e.g., 5 sparse points subsequent to thesecond group), then the pose is updated again at block 1060, however,the update may be based on some of the first group (e.g., sparse points6-10), the second group (e.g., sparse points 11-15), and the third group(e.g., sparse points 16-21). Thus, the integration may be considered asliding window or sliding list of sparse points, whereby only a setnumber of sparse points are used to estimate the pose and the sparsepoints used slides from the first group through the second and thirdgroups. One non-limiting advantage of this method may be that sparsepoints identified from earlier received image segments can be removedfrom the pose determination at block 1060 as they become old or stale.In some cases if the AR device is in motion relative to the sparsepoints, the rolling shutter effect may be reduced by removing old sparsepoints and capturing the change in pose between identified new sparsepoints.

In some embodiments, the preceding integration method may be utilizedbetween image frames, for example, as the outward-facing imaging system110 moves between capturing an image frame of FOV 315 a and capturing animage frame for FOV 315 b of FIG. 3. For example, a first group ofsparse points may be received from an image frame associated with afirst position 312 a (e.g., FOV 315 b), and the second group of sparsepoints may be received from an image frame associated with a secondposition 312 b (e.g., FOV 315 b). The sliding list method may beimplemented to reduce the rolling shutter effects between these imageframes. However, in some embodiments, it may not be necessary to retainmore than the most recent (N₂−1) sparse points from the first frame.

In another implementation, the pose determination at block 1060 may beperformed for a fixed number or block of sparse points. This method maysometimes be referred to as a block integration method. In someembodiments, each of the groups of sparse points may comprise a numberof sparse points equal to the block. For example, if the block is set to10, the fixed number (N₁) for the first group is 10, and the pose isdetermined at block 1040 upon identifying and extracting this firstgroup. Subsequently, a second group may be identified comprising thenext 10 sparse points, and the pose is updated at block 1060 using thissecond group. In some embodiments, this process may continue formultiple groups (e.g., a third, fourth, fifth, etc.). In someembodiments, when the image segments are stored in a buffer (e.g.,buffer 620 of FIG. 6, the size of the buffer may be selected andconfigured to store at least the number of sparse points that may beincluded in the block (e.g., the buffer may be selected to have a sizeconfigured to store at least 10 sparse points in the above example). Insome embodiments, the buffer may have a size restricted to only storethe number of sparse points comprised in the block.

While various embodiments of methods, devices, and systems are describedthroughout the present disclosure with reference to head-mounted displaydevices or AR devices, this is not intended to limit the scope of thepresent application, and are merely used as examples for illustrativepurposes. The methods and devices described herein may be applicable toother devices such as robotics, digital cameras, and other autonomousentities that may implement the methods and devices described herein tomap a 3D environment in which the device is location, and track themovements of the device through the 3D environment.

Additional Aspects

In a 1st aspect, a method for estimating a position of an image capturedevice within an environment is disclosed. The method comprises:sequentially receiving a first plurality of image segments, the firstplurality image segments forming at least a portion of an imagerepresenting a field of view (FOV) of the image capture device, the FOVcomprising a portion of the environment around the image capture deviceincluding a plurality of sparse points, wherein each sparse pointcorresponds to a subset of image segments; identifying a first group ofsparse points, the first group of sparse points comprising one or moresparse points that are identified as the first plurality of imagesegments are received; determining, by a position estimation system, theposition of the image capture device within the environment based on thefirst group of sparse points; sequentially receiving a second pluralityof image segments, the second plurality of image segments received afterthe first plurality of image segments and forming at least anotherportion of the image; identifying a second group of sparse points, thesecond group of sparse points comprising one or more sparse points thatare identified as the second plurality of image segments are received;and updating, by the position estimation system, the position of theimage capture device within the environment based on the first andsecond group of sparse points.

In a 2nd aspect, the method of aspect 1, further comprising sequentiallycapturing the plurality of image segments at an image sensor of theimage capture device.

In a 3rd aspect, the method of aspects 1 or 2, wherein image sensor is arolling shutter image sensor.

In a 4th aspect, the method of any one of aspects 1-3, furthercomprising storing the first and second plurality of image segments in abuffer as the image segments are sequentially received, the bufferhaving a sized corresponding to the number of image segments in thesubset of image segments.

In a 5th aspect, the method of any one of aspects 1-4, furthercomprising extracting the first and second groups of sparse points tothe position estimation system.

In a 6th aspect, the method of any one of aspects 1-5, wherein the firstgroup of sparse points comprises a number of sparse points.

In a 7th aspect, the method of aspect 6, wherein the number of sparsepoints is between 10 and 20 sparse points.

In an 8th aspect, the method of any one of aspects 1-7, wherein thesecond group of sparse points comprises a second number of sparsepoints.

In a 9th aspect, the method of any one of aspects 1-8, wherein saidupdating the position of the image capture device is based on a numberof the most recently identified sparse points, wherein the most recentlyidentified sparse points is at least one of the first group, the secondgroup, or one or more of the first group and the second group.

In a 10th aspect, the method of aspect 9, wherein the number of the mostrecently identified sparse points is equal to the number of sparsepoints in the first group of sparse points.

In an 11th aspect, the method of any one of aspects 1-10, whereinposition estimation system is configured to perform visual simultaneouslocalization and mapping (V-SLAM).

In a 12th aspect, the method of any one of aspects 1-11, wherein theplurality of sparse points are extracted based on at least one of areal-world object, a virtual image element, and a non-visible indicatorprojected into the environment.

In a 13th aspect, a method for estimating a position of an image capturedevice within an environment is disclosed. The method comprises:sequentially receiving a plurality of image segments, the plurality ofimage segments forming an image representing a field of view (FOV) ofthe image capture device, the FOV comprising a portion of theenvironment around the image capture device including a plurality ofsparse points, wherein each sparse point is identifiable based in parton a corresponding subset of image segments of the plurality of imagesegments; sequentially identifying one or more sparse points of theplurality of sparse points when each subset of image segmentscorresponding to the one or more sparse points is received; andestimating a position of the image capture device in the environmentbased on the identified the one or more sparse points.

In a 14th aspect, the method of aspects 13, wherein sequentiallyreceiving the plurality of image segments further comprises receiving anumber of image segments and storing the number of image segments in abuffer.

In a 15th aspect, the method of aspects 13 or 14, wherein sequentiallyreceiving the plurality of image segments comprises receiving at least afirst image segment and a second image segment, wherein the first imagesegment is stored in the buffer.

In a 16th aspect, the method of any one of aspects 13-15, furthercomprising: updating the buffer upon receiving a second image segment;storing the second image segment in the buffer; and, upon receiving thesecond image segment, removing the first image segment.

In a 17th aspect, the method of aspect 16, wherein sequentiallyidentifying one or more sparse points further comprises scanning theimage segments stored in the buffer when the buffer is updated.

In an 18th aspect, the method of any one of aspects 13-17, whereinsequentially identifying one or more sparse points of the plurality ofsparse points when each subset of image segments corresponding to theone or more sparse points is received further comprises: sequentiallyidentifying a first group of one or more sparse points when a firstplurality of image segments corresponding to the one or more sparsepoints of the first group is received; and sequentially identifying asecond group of one or more sparse points when a second plurality ofimage segments corresponding to the one or more sparse points of thesecond group is received, wherein the second plurality of image segmentsis received after the first plurality of image segments.

In a 19th aspect, the method of any one of aspects 13-18, whereinestimating a position of the image capture device is based onidentifying the first group of one or more sparse points, wherein thefirst group comprises a number of sparse points.

In a 20th aspect, the method of aspect 19, wherein the number of sparsepoints is between 2 and 20.

In a 21st aspect, the method of aspect 19, wherein the number of sparsepoints is between 10 and 20.

In a 22nd aspect, the method of any one of aspects 13-21, furthercomprising updating the position of the image capture device based onidentifying a second group of one or more sparse points.

In a 23rd aspect, the method of any one of aspects 13-22, wherein thesecond group of one or more sparse points comprises a second number ofsparse points.

In a 24th aspect, the method of any one of aspects 13-23, furthercomprising updating the position of the image capture device based onidentifying a number of the sequentially identified sparse points.

In a 25th aspect, the method of aspect 24, wherein the number ofsequentially identified sparse points is equal to the number of sparsepoints.

In a 26th aspect, the method of aspect 24, wherein the number ofsequentially identified sparse points comprises at least one of thesparse points of the first group of sparse points.

In a 27th aspect, the method of any one of aspects 13-26, wherein theplurality of sparse points are extracted based on at least one of areal-world object, a virtual image element, and an non-visible indicatorprojected into the environment.

In a 28th aspect, the method of any one of aspects 13-27, furthercomprising: extracting the sequentially identified sparse points fromthe buffer; and sending the sequentially identified sparse points to avisual simultaneous location and mapping (VSLAM) system, wherein theVSLAM system estimates the position of the image capture device based onthe sequentially identified one or more sparse points.

In a 29th aspect, an augmented reality (AR) system is disclosed. The ARsystem comprises an outward-facing imaging device, computer hardware,and a processor operatively coupled to the computer hardware andoutward-facing imaging device and configured to execute instruction toperform the method of any one of aspects 1-28.

In a 30th aspect, the AR system of aspect 29, wherein the outward-facingimaging device is configured to detect light in the non-visiblespectrum.

In a 31st aspect, the AR system of aspects 29 or 30, wherein the ARsystem is configured to display one or more virtual image elements.

In a 32nd aspect, the AR system of any one of aspects 29-31, furthercomprising a transceiver configured to transmit an identifying signalindicative of the estimated position of the AR system to a remote ARsystem, wherein the remote AR system is configured to update itsestimated position based on the received identifying signal.

In a 33rd aspect, an autonomous entity is disclosed. The autonomousentity comprises an outward-facing imaging device, computer hardware,and a processor operatively coupled to the computer hardware andoutward-facing imaging device and configured to execute instruction toperform the method of any one of aspects 1-28.

In a 34th aspect, the autonomous entity of aspect 33, wherein theoutward-facing imaging device is configured to detect light in thenon-visible spectrum.

In a 35th aspect, a robotic system is disclosed. The robotic systemcomprises an outward-facing imaging device, computer hardware, and aprocessor operatively coupled to the computer hardware andoutward-facing imaging device and configured to execute instruction toperform the method of any one of aspects 1-28.

In a 36th aspect, an image capture device for estimating a position ofthe image capture device in an environment is disclosed. The imagecapture device comprises: an image sensor configured to capture an imagevia sequentially capturing a plurality of image segments, the imagerepresenting a field of view (FOV) of the image capture device, the FOVcomprising a portion of the environment around the image capture deviceincluding a plurality of sparse points, wherein each sparse point isidentifiable based in part on a corresponding subset of the plurality ofimage segments; a memory circuit configured to store the subsets ofimage segments corresponding to one or more sparse points; a computerprocessor operatively coupled to the memory circuit and configured to:sequentially identify one or more sparse points of the plurality ofsparse points when each subset of image segments corresponding to theone or more sparse points is received; and extract the sequentiallyidentified one or more sparse points for estimating a position of theimage capture device in the environment based on the identified the oneor more sparse points.

In a 37th aspect, the image capture device of aspect 36, furthercomprising a position estimation system configured to: receive thesequentially identified one or more sparse points; and estimate theposition of the image capture device in the environment based on theidentified the one or more sparse points.

In a 38th aspect, the image capture device of aspects 36 or 37, whereinthe position estimation system is a visual simultaneous location andmapping (VSLAM) system.

In a 39th aspect, the image capture device of any one of aspects 36-38,wherein the image sensor is configured to detect light in thenon-visible spectrum.

In a 40th aspect, the image capture device of any one of aspects 36-39,further comprising a transceiver configured to transmit an identifyingsignal indicative of its estimated position to a remote image capturedevice, wherein the remote image capture device is configured to updateits estimated position based on the received identifying signal.

OTHER CONSIDERATIONS

Each of the processes, methods, and algorithms described herein and/ordepicted in the attached figures may be embodied in, and fully orpartially automated by, code modules executed by one or more physicalcomputing systems, hardware computer processors, application-specificcircuitry, and/or electronic hardware configured to execute specific andparticular computer instructions. For example, computing systems caninclude general purpose computers (e.g., servers) programmed withspecific computer instructions or special purpose computers, specialpurpose circuitry, and so forth. A code module may be compiled andlinked into an executable program, installed in a dynamic link library,or may be written in an interpreted programming language. In someimplementations, particular operations and methods may be performed bycircuitry that is specific to a given function.

Further, certain implementations of the functionality of the presentdisclosure are sufficiently mathematically, computationally, ortechnically complex that application-specific hardware or one or morephysical computing devices (utilizing appropriate specialized executableinstructions) or specialized graphics processing units may be necessaryto perform the functionality, for example, due to the volume orcomplexity of the calculations involved or to provide results, forexample, pose estimation inputs, substantially in real-time. Forexample, a video may include many frames, with each frame havingmillions of pixels, and specifically programmed computer hardware isnecessary to process the video data to provide a desired imageprocessing task or application in a commercially reasonable amount oftime.

Code modules or any type of data may be stored on any type ofnon-transitory computer-readable medium, such as physical computerstorage including hard drives, solid state memory, random access memory(RAM), read only memory (ROM), optical disc, volatile or non-volatilestorage, combinations of the same and/or the like. The methods andmodules (or data) may also be transmitted as generated data signals(e.g., as part of a carrier wave or other analog or digital propagatedsignal) on a variety of computer-readable transmission mediums,including wireless-based and wired/cable-based mediums, and may take avariety of forms (e.g., as part of a single or multiplexed analogsignal, or as multiple discrete digital packets or frames). The resultsof the disclosed processes or process steps may be stored, persistentlyor otherwise, in any type of non-transitory, tangible computer storageor may be communicated via a computer-readable transmission medium.

Any processes, blocks, states, steps, or functionalities in flowdiagrams described herein and/or depicted in the attached figures shouldbe understood as potentially representing code modules, segments, orportions of code which include one or more executable instructions forimplementing specific functions (e.g., logical or arithmetical) or stepsin the process. The various processes, blocks, states, steps, orfunctionalities can be combined, rearranged, added to, deleted from,modified, or otherwise changed from the illustrative examples providedherein. In some embodiments, additional or different computing systemsor code modules may perform some or all of the functionalities describedherein. The methods and processes described herein are also not limitedto any particular sequence, and the blocks, steps, or states relatingthereto can be performed in other sequences that are appropriate, forexample, in serial, in parallel, or in some other manner. Tasks orevents may be added to or removed from the disclosed exampleembodiments. Moreover, the separation of various system components inthe implementations described herein is for illustrative purposes andshould not be understood as requiring such separation in allimplementations. It should be understood that the described programcomponents, methods, and systems can generally be integrated together ina single computer product or packaged into multiple computer products.Many implementation variations are possible.

The processes, methods, and systems may be implemented in a network (ordistributed) computing environment. Network environments includeenterprise-wide computer networks, intranets, local area networks (LAN),wide area networks (WAN), personal area networks (PAN), cloud computingnetworks, crowd-sourced computing networks, the Internet, and the WorldWide Web. The network may be a wired or a wireless network or any othertype of communication network.

The systems and methods of the disclosure each have several innovativeaspects, no single one of which is solely responsible or required forthe desirable attributes disclosed herein. The various features andprocesses described above may be used independently of one another, ormay be combined in various ways. All possible combinations andsubcombinations are intended to fall within the scope of thisdisclosure. Various modifications to the implementations described inthis disclosure may be readily apparent to those skilled in the art, andthe generic principles defined herein may be applied to otherimplementations without departing from the spirit or scope of thisdisclosure. Thus, the claims are not intended to be limited to theimplementations shown herein, but are to be accorded the widest scopeconsistent with this disclosure, the principles and the novel featuresdisclosed herein.

Certain features that are described in this specification in the contextof separate implementations also can be implemented in combination in asingle implementation. Conversely, various features that are describedin the context of a single implementation also can be implemented inmultiple implementations separately or in any suitable subcombination.Moreover, although features may be described above as acting in certaincombinations and even initially claimed as such, one or more featuresfrom a claimed combination can in some cases be excised from thecombination, and the claimed combination may be directed to asubcombination or variation of a subcombination. No single feature orgroup of features is necessary or indispensable to each and everyembodiment.

Conditional language used herein, such as, among others, “can,” “could,”“might,” “may,” “e.g.,” and the like, unless specifically statedotherwise, or otherwise understood within the context as used, isgenerally intended to convey that certain embodiments include, whileother embodiments do not include, certain features, elements and/orsteps. Thus, such conditional language is not generally intended toimply that features, elements and/or steps are in any way required forone or more embodiments or that one or more embodiments necessarilyinclude logic for deciding, with or without author input or prompting,whether these features, elements and/or steps are included or are to beperformed in any particular embodiment. The terms “comprising,”“including,” “having,” and the like are synonymous and are usedinclusively, in an open-ended fashion, and do not exclude additionalelements, features, acts, operations, and so forth. Also, the term “or”is used in its inclusive sense (and not in its exclusive sense) so thatwhen used, for example, to connect a list of elements, the term “or”means one, some, or all of the elements in the list. In addition, thearticles “a,” “an,” and “the” as used in this application and theappended claims are to be construed to mean “one or more” or “at leastone” unless specified otherwise.

As used herein, a phrase referring to “at least one of” a list of itemsrefers to any combination of those items, including single members. Asan example, “at least one of: A, B, or C” is intended to cover: A, B, C,A and B, A and C, B and C, and A, B, and C. Conjunctive language such asthe phrase “at least one of X, Y and Z,” unless specifically statedotherwise, is otherwise understood with the context as used in generalto convey that an item, term, etc. may be at least one of X, Y or Z.Thus, such conjunctive language is not generally intended to imply thatcertain embodiments require at least one of X, at least one of Y and atleast one of Z to each be present.

Similarly, while operations may be depicted in the drawings in aparticular order, it is to be recognized that such operations need notbe performed in the particular order shown or in sequential order, orthat all illustrated operations be performed, to achieve desirableresults. Further, the drawings may schematically depict one more exampleprocesses in the form of a flowchart. However, other operations that arenot depicted can be incorporated in the example methods and processesthat are schematically illustrated. For example, one or more additionaloperations can be performed before, after, simultaneously, or betweenany of the illustrated operations. Additionally, the operations may berearranged or reordered in other implementations. In certaincircumstances, multitasking and parallel processing may be advantageous.Moreover, the separation of various system components in theimplementations described above should not be understood as requiringsuch separation in all implementations, and it should be understood thatthe described program components and systems can generally be integratedtogether in a single software product or packaged into multiple softwareproducts. Additionally, other implementations are within the scope ofthe following claims. In some cases, the actions recited in the claimscan be performed in a different order and still achieve desirableresults.

What is claimed is:
 1. An imaging system comprising: an image capturedevice comprising a lens and an image sensor, the lens configured todirect light from an environment surrounding the image capture device tothe image sensor, the image sensor configured to: sequentially capture afirst plurality of image segments of an image based on the light fromthe environment, the image representing a field of view (FOV) of theimage capture device, the FOV comprising a portion of the environmentand including a plurality of sparse points, and sequentially capture asecond plurality of image segments, the second plurality of imagesegments captured after the first plurality of image segments andforming at least another portion of the image; non-transitory datastorage configured to sequentially receive the first and secondplurality of image segments from the image sensor and store instructionsfor estimating at least one of a position and orientation of the imagecapture device within the environment; and at least one hardwareprocessor operably coupled to the non-transitory data storage andconfigured by the instructions to: identify a first group of sparsepoints based in part on a corresponding subset of the first plurality ofimage segments, the first group of sparse points identified as the firstplurality of image segments are received at the non-transitory datastorage, determine at least one of the position and orientation of theimaging device within the environment based on the first group of sparsepoints, identify a second group of sparse points based in part on acorresponding subset of the second plurality of image segments, thesecond group of sparse points identified as the second plurality ofimage segments are received at the non-transitory data storage, andupdate the at least one of the position and orientation of the imagingdevice within the environment based on the first and second group ofsparse points.
 2. The imaging system of claim 1, wherein the imagesensor is a rolling shutter image sensor.
 3. The imaging system of claim1, wherein the non-transitory data storage comprises non-transitorybuffer storage configured to sequentially receive the first and secondplurality of image segments as the image segments are captured by theimage sensor, the non-transitory buffer storage having a storagecapacity based at least partly on a number of image segments included ineach subset of image segments.
 4. The imaging system of claim 1, whereinthe first group of sparse points or the second group of sparse pointscomprises a number of sparse points between 10 and 20 sparse points. 5.The imaging system of claim 1, wherein the hardware processor isconfigured to update the at least one of the position and orientation ofthe image capture device based on a number of the most recentlyidentified sparse points, wherein the most recently identified sparsepoints comprises at least one of the first group of sparse points, thesecond group of sparse points, and one or more of the first and thesecond group of sparse points.
 6. The imaging system of claim 5, whereinthe number of the most recently identified sparse points is equal to anumber of sparse points in the first group of sparse points.
 7. Theimaging system of claim 1, wherein the hardware processor is configuredto perform a visual simultaneous localization and mapping (V-SLAM)algorithm.
 8. The imaging system of claim 1, wherein the plurality ofsparse points are identified based on at least one of a real-worldobject, a virtual image element, and a non-visible indicator projectedinto the environment.
 9. A head mounted display (HMD) configured to beworn on the head of a user, the HMD comprising: a frame; a displaysupported by the frame and disposed forward of an eye of the user; anoutward facing image capture device disposed on the frame and comprisinga lens and an image sensor, the lens configured to direct light from anenvironment surrounding the HMD to the image sensor and the image sensorconfigured to sequentially capture a plurality of image segments of animage based on the light from the environment, the image representing afield of view (FOV) of the outward facing image capture device, the FOVcomprising a portion of an environment and including a plurality ofsparse points, wherein each sparse point is identifiable in part basedon a corresponding subset of the plurality of image segments;non-transitory data storage configured to sequentially receive theplurality of image segments from the image sensor and store instructionsfor estimating at least one of a position and orientation of the HMDwithin the environment; and at least one hardware processor operablycoupled to the non-transitory data storage and configured by theinstructions to: sequentially identify one or more sparse points of theplurality of sparse points when each subset of image segmentscorresponding to the one or more sparse points is received at thenon-transitory data storage, and estimate the at least one of theposition and orientation of the HMD within the environment based on theidentified the one or more sparse points.
 10. The HMD of claim 9,wherein the non-transitory data storage comprises a circular or rollingbuffer.
 11. The HMD of claim 9, wherein the plurality of image segmentscomprises at least a first plurality of image segments and a secondplurality of image segments, and wherein the image sensor is configuredto sequentially transmit the first and second image segments to thenon-transitory data storage.
 12. The HMD of claim 11, wherein thehardware processor is configured to: sequentially identify a first groupof one or more sparse points when the first plurality of image segmentscorresponding to the one or more sparse points of the first group isreceived; and sequentially identify a second group of one or more sparsepoints when the second plurality of image segments corresponding to theone or more sparse points of the second group is received, wherein thesecond plurality of image segments is received after the first pluralityof image segments.
 13. The HMD of claim 12, wherein the hardwareprocessor is configured to estimate the at least one of the position andorientation of the HMD based on the identified first group of one ormore sparse points.
 14. The HMD of claim 13, wherein the first group ofsparse points or the second group of sparse points comprises a number ofsparse points between 2 and
 20. 15. The HMD of claim 13, wherein thefirst group of sparse points or the second group of comprises a numberof sparse points between 10 and
 20. 16. The HMD of claim 13, wherein thehardware processor is further configured to update the at least one ofthe position and orientation of the HMD based on the identified secondgroup of one or more sparse points.
 17. The HMD of claim 9, wherein thehardware processor is further configured to update the at least one ofthe position and orientation of the HMD when a number of thesequentially identified one or more sparse points are identified. 18.The HMD of claim 17, wherein the number of sequentially identified oneor more sparse points comprises at least one of the sparse points of thefirst group of one or more sparse points.
 19. The HMD of claim 9,wherein the plurality of sparse points are identified based on at leastone of a real-world object, a virtual image element, and a non-visibleindicator projected into the environment.
 20. The HMD of claim 9,wherein the hardware processor is further configured to: extract thesequentially identified one or more sparse points from the correspondingsubset of the plurality of image segments; and perform a visualsimultaneous location mapping (VSLAM) algorithm on the sequentiallyidentified one or more sparse points to estimate the at least one of theposition and orientation of the image capture device.